
Well, he killed for fun. It is kind of the argument people have for killing animals. Killing animals for food is like that food chain thing it is humane since it is only eating to live—but when animal are abused and killed in ways that torment the animals then it is abuse and you can get into trouble for it. There is a difference between killing for food and killing for amusement. One is seen as acceptable, while the other isn't so it's kinda hard to see him in the same light as the demons since he does it because he wants to. Their is no strain on his life/health if he doesn't kill a person.

....the main couple are NOT human you are missing the main point. Their instincts are to kill and EAT humans just like humans eat pigs and chickens. Humans however are NOT meant to kill each other. The main couple needs a good ending no matter how shitty things might go for the serial killer and the cop.

I found them more... alarming. They didn't bring out the best in each other. They hadn't grown in any way healthy with one another. I think if the killer had gotten mental help that he would've been better since he's so smart. It could've been put to use that wouldn't have landed him in jail. But I think their characters display the 'monsters in humanity' and they just couldn't end with a good ending. The main couple is a whole lot of eye candy though.

You felt bad for the serial killer?

I don't think Sealwoo killed for fun. Context, his dad killed his mum and then went on the run, therefore he has already witnessed murder at a young age. This was where he met the detective who became his "light". Sealwoo refers to himself as being dark and wants his light to always be there, he thinks his "light" is good because he 'catches bad guys", he was a traumatised kid when they had this conversation so he probably found this more profound than the detective intended it to be. Therefore Sealwoo tries to get his "light" to shine, by essentially giving him work chasing those bad guys (or really he kills people and then the detective tries to looks and blame innocent folk like the vampire), and by being that dark contrast. Sealwo was a damaged kid at the end of the day, and his perspective was warped. But his primary motivation was because he loved the detective and this was how it was manifested. It's messed up, but it is what it is. Sealwoo wasn't some unfeeling man who killed people just for "fun" in the plot it shows his motivations quite clearly.
The last chapter of him sitting alone and restrained in a prison or hospital is quite sad, but I doubt he would have ended up a free man.

RAW LINK: https://toonkor.xyz/나의-피와-영혼을-그대에게
I realised it after in posted it sorry fam..
I know he’s a serial killer and all but the way the purple haired lady kind of toyed with him made me feel bad for him.
I mean, both the main characters have killed hundreds of people[albeit only to eat but they’re both implied to kind of enjoy it] so really he’s no more morally abhorrent than either of the mains.
I think I’ll feel bad if the main couple gets to have a happy ending and the serial killer and cop couple don’t.